Along with improvements in the speed of nonvolatile semiconductor memory storage device, there is a corresponding increase in heat generation in the components of the device as well as an increase in power consumption by the device. Furthermore, with the miniaturization of the devices, components are now closer together, so even if the same quantity of heat is generated by a heat generating component in the device, it will be easy for other components to be subject to the influence of the heat due to the miniaturization of the device. Heat generation is significant in the portion of the controller of the device that is responsible for various tasks. The influence of heat from the controller on the reliability of the nonvolatile semiconductor memory storage device affects other components, which may shorten the lifetime of the other components and/or reduce the performance of other components.